Understanding Visual Impairment: Conditions, Causes, and Support

Understanding Visual Disability

To better comprehend visual disability, it's important to distinguish between related concepts:

• Deficiency

  A loss or abnormality of psychological, physiological, or anatomical structure or function. Example: An alteration of the cornea.

• Disability

  A restriction or inability to perform an activity in the manner or within the range considered normal for a human being. Example: Difficulty distinguishing colors or judging the distance of objects.

• Handicap

  A disadvantage for a given individual, resulting from a deficiency or disability, that limits or prevents the fulfillment of a role that is normal (depending on age, sex, social and cultural factors) for that individual. Example: Being blind in a society not adapted for the visually impaired.

What is Visual Impairment?

Visual impairment refers to the absence, decrease, or defect of vision. This can arise from various causes:

• Congenital Causes

  Conditions that are hereditary or present from birth.

• Acquired Causes

  Conditions developed later in life due to accidents, illnesses, or other external factors.

Common Eye Conditions Affecting Vision

Conditions Affecting the Optic Nerve

• Optic Atrophy

  Affects the perception of form and color due to damage to the optic nerve.

Abnormalities Affecting Intraocular Pressure

• Glaucoma

  A group of eye conditions that damage the optic nerve, often due to abnormally high pressure inside the eye. It can lead to visual field defects and, if untreated, blindness.

Abnormalities Affecting Ocular Motility

• Nystagmus

  Characterized by involuntary, rapid, and repetitive eye movements, leading to imperfect vision.

• Strabismus

  A deviation of the eyes in the primary and cardinal positions of gaze, where one eye is fixed while the other is misaligned. This can be:

  • Convergent Strabismus: Inward deviation of the eye.
  • Divergent Strabismus: Outward deviation of the eye.

Ocular Refractive Errors

• Myopia (Nearsightedness)

  An anomaly that prevents or impairs clear distant vision, causing a blurred image. It is classified as:

  • Simple Myopia: Typically does not advance significantly and may even improve.
  • Degenerative Myopia: A more severe form that progresses over time, potentially leading to significant vision loss.

• Hyperopia (Farsightedness)

  A condition where distant objects may appear clearer than near objects, or both may be blurred, due to the eye focusing light behind the retina.

• Astigmatism

  An eye condition caused by an irregular curvature of the cornea or lens, which prevents the clear focus of objects both far and near, resulting in distorted or blurred vision.

• Presbyopia

  A common age-related condition causing difficulty focusing on close objects. It's often referred to as "farsightedness" or "old sight" due to the natural hardening of the eye's lens, making near vision tasks challenging while distant vision remains stable.

Amblyopia (Lazy Eye)

The deterioration of vision in one eye due to lack of use during critical developmental periods. It is commonly known as "lazy eye."

Consequences of Amblyopia

• Strabismus (eye misalignment)
• Excessive upper eyelid droop (ptosis)
• Lack of adequate visual stimulation

Treatments for Ocular Refractive Errors

• Glasses
• Contact Lenses (soft or rigid)
• Laser Eye Surgery (e.g., LASIK)
• Intraocular Lens Implants

Key Visual Impairments

Beyond refractive errors, other significant visual impairments include:

1. Decreased Visual Acuity

   Characterized by blurred vision or dark spots (nebulae).

2. Pathological Alterations of the Visual Field

   Visual field defects can include peripheral constrictions and scotomas (blind spots).

3. Changes in Color Perception

   Involves the loss of perception of one or more primary colors (red, green, or blue), often due to errors in color matching.

4. Anomaly Related to Ambient Brightness

   An alteration of the retina's sensitivity to light intensity, which can produce effects that impair vision, such as photophobia (light sensitivity) or nyctalopia (night blindness).

Degrees of Visual Deficiency

• Totally Blind

  Complete lack of vision.

• Partially Blind

  Residual visual orientation that allows the perception of light and mass.

• Profound Amblyopic

  Residual vision that defines volumes and color perception.

• Amblyopic (itself)

  Vision that requires close proximity and particular teaching methods.

ONCE: National Organization of Spanish Blind

ONCE (Organización Nacional de Ciegos Españoles) is a non-profit corporation dedicated to improving the quality of life for people with visual disabilities in Spain.

Guidelines for Students with Low Vision from ONCE

ONCE recommends a set of guidelines to enhance the autonomy and visual development of visually impaired individuals, including:

• Encouraging and coordinating movements.
• Working with contrasting colors (especially light and dark).
• Teaching safety skills.
• Setting appropriate expectations and requirements.
• Emphasizing the important role of parents in support and development.

Multisensory Stimulation for Visual Impairment

Multisensory stimulation is crucial for individuals with visual impairments, fostering development through various senses:

• Tactile Stimulation
• Perceptual-Auditory Stimulation
• Olfactory and Gustatory Stimulation
• Visual Stimulation (where applicable)

Adaptive Sports for the Visually Impaired

Participation in adaptive sports promotes physical activity, social interaction, and overall well-being for individuals with visual impairments. Examples include:

• Chess
• Athletics
• Cycling (Tandem)
• Skiing
• Futsal (Indoor Soccer)
• Goalball